Pressure recovery from bistable element



R. w. WARREN ET AL 3,225,780

PRESSURE RECOVERY FROM BISTABLE ELEMENT Dec. 28, 1965 2 Sheets-Sheet 1Filed May 20, 1963 Z we M w. W W m W m 2 "1.

BY g4 1 Dec. 28, 1965 w. WARREN ETAL 3,

PRESSURE RECOVERY FROM BISTABLE ELEMENT Filed May 20, 1963 2Sheets-Sheet 2 United States Patent 3,225,780 PRESSURE REQUVERY FRQMBISTABLE ELEMENT Raymond W. Warren, McLean, Va., and Ralph G.

Barclay and John G. Moorhead, Silver Spring, Md, assignors to the UnitedStates of America as represented by the Secretary of the Army Filed May20, 1963, Ser. No. 281,847 8 Claims. (Cl. 137-815) (Granted under Title35, US. Code (1952), see. 266) The invention described herein may bemanufactured and used by or for the Government for governmental purposeswithout the payment to me of any royalty thereon.

This invention relates generally to pure fluid systems and morespecifically to a self-adaptive pure fluid system which incorporates apure fluid amplifier therein.

A typical pure fluid amplifier that is preferably incorporated in theself adaptive fluid system of this invention includes an interactionchamber defined for example by an end wall and .two outwardly divergingsidewalls, hereinafter referred to as the left and right sidewalls. Anozzle having an orifice in the end wall is provided to issue awell-defined and relatively large energy stream, hereinafter referred toas a power stream, into the interaction chamber. A substantiallyV-shaped flow divider has one end thereof disposed a predetermineddistance from the end wall, the sides of the divider being generallyparallel to the left and right sidewalls of the chamber. The regionsbetween the sides of the divider and the left and right sidewalls defineleft and right output passages, respectively.

Fluid control signals in the form of control streams are supplied by acontrol nozzle to the interaction chamber, the control nozzle beingpositioned generally perpendicularly to the power nozzle. The powerstream is deflected in the interaction chamber by interaction with thefluid of the control stream, the smaller energy of the control streamcontrolling the larger energy of the power stream so that amplificationis achieved. Since no moving mechanical parts are required for operationof such amplifiers they are known and referred to by those working inthe art as pure fluid amplifiers.

In accordance with this invention, the following types of pure fluidamplifier units can be constructed and embodied in the fluid pressurerecovery system of the instant invention.

Fluid amplifiers wherein the control and power streams interact in sucha way that the resulting flow patterns and pressure distribution intothe output passages are greatly affected by the details of the design ofthe sidewalls. The effect of sidewall configuration on the flow patternsand pressure distribution which can be achieved depends upon: therelation between width of the power nozzle supplying the fluid stream tothe chamber and the distance between opposite sidewalls of theinteraction chamber adjacent the orifice of the power nozzle; the anglethat the sidewalls make with respect to the centerline of the powerstream; the length of the sidewall (when a flow divider is not used);the spacing between the power nozzle and the flow divider (if used); andthe density, viscosity, compressibility and uniformity of the fluidflowing in the chamber. It also depends to some extent on the thicknessof the fluid element. In general, fluid devices utilizing boundary layereffects, i.e., effects which depend upon details of sidewallsconfiguration can be subdivided into three categories:

(a) Boundary layer elements in which there is no appreciable lock oneffect. Such a unit has a power gain which can be increased by boundarylayer effects, but these effects are not dominant;

3,2538% Patented Dec. 28, 1965 (b) Boundary layer units in which lock-oneffects are dominant and are sufficient to maintain the power stream ina particular flow pattern through the action of the pressuredistribution arising from boundary layer effects, and requiring nostreams other than the power stream to maintain that flow pattern, onceestablished, but having a flow pattern which can be changed to a newstable flow pattern by control stream flow, or by altering the pressuresat one or more of the output passages;

(0) Boundary layer units in which the flow pattern can be maintainedthrough the action of the power stream along without being continuouslycontrolled by control stream flow. The flow pattern in this type of unitcan be modified by the application of a control stream but otherwisemaintains the power stream flow pattern, including lock on to thesidewall, even though the pressure distribution at the output passagesis increased.

The lock-on phenomena referred .to hereinabove is due to a boundarylayer effect existing between the stream and a sidewall. Assumeinitially that the fluid stream is issuing from the power nozzle and isdirected toward the apex of the divider. The fluid issuing from thepower nozzle orifice, in passing through the chamber, entrains fluid inthe chamber and removes this fluid therefrom. If the power stream isslightly closer to, for instance, the left wall than the right wall, itis more effective in removing the fluid in the region between the streamand the left wall than it is in removing fluid between the stream andthe right wall. There-fore, the pressure in the left region between theleft wall and stream is lower than the pressure in the right region ofthe chamber and a differential pressure is set up across the powerstream tending to deflect it toward the left wall. As the power streamis deflected further toward the left wall, it becomes even moreefficient in entraining air in the left region and the pressure in thisregion is further reduced. This action is self-reinforcing and resultsin the power stream becoming deflected toward the left wall and enteringthe left outlet passage. The stream intersects the left wall at apredetermined distance downstream from the outlet of the main orifice;this point being normally referred to as the point of attachment. Thisphenomena is referred to as boundary layer lock on. The operation ofthis type of apparatus may be completely symmetrical in that if thestream had initially been slightly deflected toward the right wallrather than the left wall, boundary layer lock on would have occurredagainst the right wall.

Continuing the discussion of the three categories of the second class ofbeam type fluid amplifying units, the boundary layer unit type a aboveutilizes a combination of boundary layer effects and momentuminteraction between streams in order to achieve a power gain which isenhanced by the boundary layer effects, but since boundary layer effectsin type a are not dominant, the power stream does not of itself remainlocked to the sidewall. The power stream remains diverted from itsinitial direction only if there is a continuing control flow thatinteracts to maintain the deflection of the power stream. Boundary layerunit type b has a suflicient lock on effect that the power streamcontinues to fiow entirely out one passage in the absence of any fluidcontrol signal. A boundary layer unit type b can be made as a bistableunit, but it can be dislodged from one of its stable states by controlfluid flow or by the blocking of the output passage connected to theaperture receiving the major portion of the power stream. Boundary layerunits type 0 have a very strong tendency to maintain the direction offlow of the power stream through the interaction chamber, this tendencybeing so strong that complete blockage of the passage connected to oneof the output apertures toward which the power stream is directed doesnot dislodge the power stream from its locked on condition. Boundarylayer units type c are therefore memory units which while sensitive tointeracting control fluid flow, are relatively insensitive to positiveloading conditions at their output passages.

To give a specific example: boundary layer effects have been found toinfluence the performance of a fluid amplifier element if it is made asfollows: the width of the interacting chamber at the point where thepower nozzle issues its stream is two to three times the width, W, ofthe power nozzle, i.e., the chamber width at this oint is 3W; and thesidewalls of the chamber diverge so that each sidewall makes a 12 anglewith the center line of the power stream. In a unit made in this way, aspacing between the power nozzle and the center divider equal to twopower nozzle widths 2W will exhibit increased gain because of boundarylayer effects, but the stream will not remain locked on either side.This unit with a divider spacing of 2W is a boundary layer unit type awhich if the spacing is less than 2W an amplifier of the first class,i.e., a proportional amplifier results. If the di vider is spaced morethan three power nozzle widths 3W, but less than eight power nozzlewidths, 8W, from the power nozzle, then the power stream remains lockedonto one of the chamber walls and is a boundary layer type b. Asubstantial blockage of the output passage of such a unit generallycauses the power stream to take a new flow pattern into the adjacentoutput passage if that passage is not blocked.

A boundary layer unit having a divider which is spaced more than twelvepower nozzle widths 12W, from the power nozzle remains locked on to achamber Wall even though there is almost a complete blockage of theoutput passage into which the power stream is directed, and thus it is aboundary layer unit type c. Another factor effecting the type ofoperation achieved by these units is the pressure of the fluid appliedto the power nozzle relative to the width of the chamber. In the aboveexamples, the types of operation described are achieved if the pressureof the fluid is less than 60 psi. If, however, the pressure exceeds 80p.s.i. the expansion of the fluid stream upon issuing from the powernozzle is sufliciently great to cause the stream to contact bothsidewalls of the chamber and lock-on is prevented. Lock-on can beachieved at the higher pressures by increasing the widths of theinteraction chamber.

In general, the output passages of the aforedescribed pure fluidamplifier are connected to drive loads such as pistons or to varioustypes of pure fluid systems, known to those working in the art. Sincemany types of load utilization devices require pressure for theoperation or control thereof, the fluid flow from the pure fluidamplifier must be converted to a fluid pressure head which preferablyincreases as the load increases.

As the load into which the output flow from the aforedescribed purefluid amplifiers increases, lock-on will exist in the class c type ofamplifier, and may continue to exist in the class b type of amplifierdepending upon the amount of output passage backloading. However, thepressure will not rapidly build up as desired since the fluid from thepower stream under increased backloading will flow back and around theapex of the flow divider and into an adjacent output passage. Therefore,the greater the backloading of, for example, the left output passage,the greater the flow from the right output passage and generally thepressure applied to the load will not increase at a high enough rate toprovide a constant output pressure to the load.

According to this invention, a self adaptive fluid system is providedthat incorporates a pure fluid amplifier preferably of the typedescribed hereinabove. The system provides maximum pressure or flow whenmaximum pressure or flow are respectively required at the output load,and is designed to effect an impedance match between the load device andthe pure fluid amplifier incorporated in the system by a novel ductconfiguration.

Broadly, therefore, it is an object of this invention to provide a selfadaptive pure fluid system that incorporates a novel duct configurationfor effecting an automatic impedance match between the system and a loadapplied to the output of the system, even if both outputs are blocked.

The above and still further objects, features and advantages of thepresent invention will become apparent upon consideration of thefollowing detailed description of one specific embodiment thereof,especially when taken in conjunction with the accompanying drawings,wherein:

FIGURE 1 illustrates a self adaptive pure fluid system constructed inaccordance with this invention and the flow pattern of the fluid in thesystem when an output passage is backloaded;

FIGURE 2 illustrates the flow pattern in the self adaptive system ofthis invention when an output passage is partially backloaded; and

FIGURE 3 illustrates the flow pattern in the self-adaptive fluid systemof this invention when the output passage is almost completely blockedby backloading.

Referring now to FIGURE 1 for a more complete understanding of thisinvention, there is shown a self adaptive pure fluid system which isformed between two flat plates 11 and 12 sealed one to the other byadhesives, machine screws, or other suitable means. The plates 11 and 12may be composed of any material compatible with the fluid employed inthe system 10 and for purposes of illustration are shown to be composedof a clear plastic material. The configuration required to provide thesystem 10 is formed in the lower plate 11 by molding, etching, or othersuitable techniques and the plate 11 is thereafter covered with theplate 12 so that the various passages, ducts and nozzles are enclosedand sealed in a fluid-tight relationship between the two plates.

The system 10 incorporates a pure fluid amplifier shown enclosed by thedotted block 13 in FIGURE 1, the pure fluid amplifier 13 including apower nozzle 14, control nozzles 15 and 16 and interaction chamber 17.Tubes 21), 21 and 22 are respectively threadedly connected to thenozzles 14, 15 and 16, respectively, the tubes being connected tosources of fluid for supplying a power stream to the power nozzle 14 andcontrol streams to the control nozzles 21 and 22. The flow divider 27has symmetrically tapering sidewalls 30 and 31 the sidewalls beinglocated symmetrically with respect to a centerline taken through thepower nozzle 20 and located equidistances from the diverging sidewalls25 and 26 of the interaction chamber 17.

The flow divider 27 terminates at a concave tip or apex 32 which ispositioned to directly receive the power stream issuing from the powernozzle 14. The sidewalls which are positioned in opposed relationshipwith respect to the sidewalls 30 and 31 of the flow divider 27 are notcontinuous, the sidewall sections 25 and Z6 terminate at cusps 33 and34, respectively. The sidewall sections 25:: and 26a, respectively, areformed by apices 35 and 36, respectively, which are spaced a relativelyshort distance down-stream at the cusps 33 and 34, as illustrated. Asillustrated in FIGURE 1, the sidewall sections 25a and 26a are set backfrom the apices 33 and 34 of the sidewall sections 25 and 26,respectively, and therefore the lateral distance between the sidewallsection 25 and the sidewall 30 is smaller than the lateral distancebetween the sidewall section 25a and the sidewall 30. correspondinglythe lateral distance between the sidewall section 26 and the sidewall 31of the flow splitter 27 is less than the lateral distance between thesidewall section 26:: and the sidewall 31. The cusp 33 and the apex 35define opposite sides of the entrance to a duct or passage 40 and thecusp 34 and the apex 36 define opposite sides of the entrance to a ductor passage 41.

The flow divider 27 is formed with an essentially concave tip 32 againstwhich the power stream issuing from the power stream 14 will impingewith high velocity so as to create a high pressure region at a pointsubstantially at the center of the tip 32 and a vortex V3 in theinteraction chamber 17. The high pressure region created in the tip 32will be sufficient to seal 01f fluid flow which might otherwise flowaround the tip of the flow divider 27 and into an output passage.

The concave tip divider raises the pressure in the interaction region 17beyond that which would be developed in the interaction chamber 17 ifthe tip were rounded, pointed, or of some shape other than concave. Apair of ducts 40 and 41 are provided with sidewalls 42, 43 and 44, 45,respectively, that may diverge only slightly or that may be parallel.

The sidewalls 25 and 26 are set back from the orifice of the powernozzle 14 a distance such that the power stream has a tendency to lockon to the sidewalls 25 and 26 at points B1 and B, respectively, whencontrol streams from control nozzles 16 and 15, respectively, displacethe power stream in the interaction chamber 17. In general, highpressure regions or points of boundary layer attachments are produced bythe power stream impinging at relatively high velocity against asurface. Such high pressure regions tend to seal off the downstream flowof the stream from feeding back through the high pressure region. Thus,once a high pressure region is created by deflection of a high velocitystream, the pressure of the fluid downstream of the region will have toexceed the pressure of the region before the point of attachment will bedisturbed. As the pressure downstream of the point of attachmentincreases and exceeds that of the point of attachment the point ineffect moves upstream to a new location until the pressure between thepoint of attachment and the surface exceeds the increased downstreampressure. Thus, it is possible to have the point of attachment movealong the sidewalls of either the chamber 17 or the flow splitter 27 asa result of increasing and decreasing pressure downstream of the pointof attachment.

In order to understand the operation of the pure fluid system 10,illustrated in FIGURE 1, assume that the power nozzle 14 is issuing apower stream into the interaction chamber 17. If a control stream isdirected from the control nozzle into the interaction chamber it willtend to displace the power stream into the output pas sage 48. Thesidewall 26 is positioned sufliciently close to the orifice of the powernozzle 14 so that boundary layer attachment occurs at point B and mayoccur at point C depending upon the amount or quantity of flow from thepower nozzle 14 and the width of the passage between the sidewallsection and the opposite section of sidewall 31. If the quantity of flowfrom the nozzle 14 is insuflicient to completely fill the passagebetween the section 26 and the sidewall 31, the power stream will attachto the wall section closest to the edge of the stream. Thus, the pointsB and C or alternatively, the point B or the point C may each representpoints of attachment of the power stream and the control streamentrained in the power stream.

A portion of the combined power and control stream will also be directedagainst the concave tip 32 of the divider 27 at the point E. The point Bwill also be a high pressure region because the cusp 32 is positioned toreceive direct impingement of the power stream. A vortex V represents ahigh pressure region in the interaction chamber 17 will be created as aresult of fluid impinging against the tip of the apex 32. The vortex Vrotates clockwise as illustrated in FIGURE 1 and tends to suck fluidfrom the duct 40 and from the output passage 47 into the entrance of theoutput passage 48. The fluid stream flowing over the apex 34 of thesidewall section 26 reattaches at the point D to the sidewall section26a and issues from the output passage 48 along with fluid sucked fromthe duct 41 into the stream passing across the apices 34 and 36 atrelatively high velocity. Thus, in the absence of any backloading of theoutput passage 48 maximum flow will issue from that passage because ofthe entrainment of fluid from the ducts 4t and 41 and from the outputpassage 47.

Referring now to FIGURE 2, there is illustrated the flow pattern whichresults as the backloading in the output passage 48 increases as aresult of increasing the load which may for example take the form of apiston 50. As a result of the increasing pressure in the output passage48 the velocity decreases and the point of attachment D is effectivelymoved upstream to a position closer to the apex 36 as illustrated inFIGURE 2. Similarly the points of attachment B and C move upstream, thepoint C ultimately coinciding with the concave end 32 of the divider 27.A recirculating vortex V1 may now be created between the apices 34 and36 by flow across the entrance of the duct 41 from the apex 34 to thepoint of attachment D and the pressure of the vortex V1 may besufficient to prevent any fluid entering the output passage 48 from theduct 41, the vortex V1 increasing in pressure as the point D movesupstream towards the apex 36. The high pressure region created by thevortex V is now sufficient to stop any appreciable flow from the outputpassage 47 or the duct 40 into the interaction chamber 17. As fluidflows over the tips of the cusps and into the ducts 40 and 41, the cusps33 and 34 generate vortices such as the vortex V1 in the duct 41. Thusas the back pressure in the associated output passage increases thevortex V increases in velocity. The vortex V in the duct 41 rotatingcounterclockwise ensures a uniform distribution of flow output betweenthe sidewalls of the duct 41.

Referring now to FIGURE 3, there is shown the flow patterns which resultin the self adaptive system 10 when the output passage 48 is blocked bythe progressively increasing force applied to fluid egressing from theoutput passage 48 by the piston 50 that is movable in a closed cylindersystem connected to receive fluid from either output passage 47 or 48.The greatly increased pressure in the output passage 48 which iscorrespondingly created by the increased backloading of that outputpassage causes the point of attachment D to move to a position at theapex 36. Thus the fluid from the power stream turns with a radius ofcurvature substantially about the apex 34 and impinges against thesidewall 44 adjacent the apex 36 thereby creating a high pressure regionat that point. A portion of the fluid from the power stream will nowegress from the duct 41 because of the movement of the point ofattachment D into that duct, as illustrated in FIGURE 3. The point Dlocated in the duct 41 defines the downstream point of attachment. Ineffect the ambient pressure in channel 41 prevents fluid from flowingupstream to the point B.

When flow is from the left output passage in FIGURE 3, the piston 50will move to the right forcing fluid into the downstream end of theright output passage. Because the cusp 33 extends laterally outwardlyfrom the downstream sidewall section, the fluid flowing into the rightoutput passage as indicated by the arrows, the flow tends to be scoopedinto, and thereby flow into, the duct 40. Fluid which does not enter theduct 40 continues to flow upstream into the interaction chamber 17 whereit reinforces the vortex V3 and ultimately enters the left outputpassage to reinforce flow from that passage.

The reduced flow out passage 48 increases the flow out of passage 41 andmore flow reinforces the vortex V raising the pressure in theinteraction region 17 and the controls 15 and 16. This vortex forces thepower jet stream toward the wall 26. The vortex V increases in velocityas the flow across the tip of the cusp 34 increases and thus tends tomaintain uniform flow from the duct 41.

From the foregoing description of operation it will be apparent to thoseworking in the art that a maximum pressure is produced by the system 10when a maximum load is applied to the output passage and that a maximumflow results when the back-loading of the output passage is minimum. Asillustrated in the accompanying drawing, the sidewall sections 25a and26a are set back from the sidewall sections 25 and 26. Such setback ispreferable because the possibility of undesired oscillation of thesystem llll'is minimized and the amount of fluid which would bleed fromthe ducts 4th and 41 is reduced. The vortices created by the flow in thesystem which includes the setback of sidewall sections 25a and 26a andthe cusps 33 and 34 enable the sidewalls of ducts 40 and 41 to be madeessentially parallel without creating oscillation in the system 10. Animpedance match between the flow and pressure in channel 48 caused byload 50, the flow and pressure in passage 41 and the flow and pressurein the interaction region 17 is thereby accomplished withoutoscillation.

With regard to impedance matching in general, it is known to thoseskilled in the art that if a moving column of fluid meets an abruptdiscontinuity in the system, a reflected wave will be produced whichtravels the length of the column of fluid as a sinusoidal oscillatingwave. An abrupt discontinuity may for example take the form ofrelatively abrupt change in flow direction as for example by a rightangle bend between a passage and a tube or pipe or by an abrupt changeof pressure between the fluid in the tube or pipe and a pressure of theregion into which the fluid discharges. An abrupt discontinuity in apure fluid system reflects shock waves which create oscillations in thefluid flowing in the passage or tube in the same manner that a pipeorgan produces standing waves in the air columns of each pipe; that is,nodes or antinodes are produced by the abrupt discontinuity which causefundamental and overtone oscillations in the air columns. As will beappreciated by those working in the art, oscillating shock waves createdby abrupt discontinuities are generally undesirable in pure fluidsystems because they create high levels of noise and tend to causeunanticipated oscillation of the unit. By providing a diverging duct tofluid output flow from the system it a relatively smooth transistion isprovided between the fluid pressure in the system and the ambientpressure of fluid egress. Thus, the impedance of the ambient pressureconditions and the impedance of the output from the system 10 aresomewhat matched by the divergence of the ducts 40 and 41 and thepossibility of unanticipated oscillation in the system 10 accordinglyreduced.

Although the entrances to the ducts 40 and 41 are illustrated in thefigures of the accompanying drawing as positioned downstream of the tip32, the entrances may alternatively be positioned upstream of the tip 32as long as they remain downstream of the points of attachment B and B1.If the entrances are positioned upstream of the points of attachment Band B1 then the flow will enter the low pressure separation region fromthe ducts 40 or 41 directly resulting in instability. The positioning ofthe entrances to the ducts 40 and 41 is determined primarily by thevelocity of the power stream anticipated at the point of attachment B.As will be obvious from the foregoing description it is important thatthe point of attachment D receive fluid with a velocity high enough toseal off the pressure downstream of the point D.

The position of the tip 32 relative to the orifice of the power nozzle14 is also determined by the velocity of the fluid impinging against thecusp 32. Optimum sealing results when the cusp 32 is positioned in thehigh velocity portion of the power stream.

Since vortices, such as the vortex V are formed by fluid flow over thetips of the cusps 33 and 34, and since such vortices provide uniformoutput flow from the ducts 40 and 41, the divergence of the sidewalls ofthe ducts 40 and 41 is essentially noncritical. The uniform flow createdby cusps and the vortices rotating therein tend to reduce thepossibility of oscillations in the ducts 4t and 41, and consequently thesidewalls of the ducts 40 and 41 may be made substantially parallel, ifdesired.

While we have described and illustrated one specific embodiment of ourinvention, it will be clear that variations of the details ofconstruction which are specifically illustrated and described may beresorted to without de parting from the true spirit and scope of theinvention as defined in the appended claims.

V-lhat we claim is:

l. A pure fluid system comprising an interaction chamber for receivingand confining fluid flow, a power nozzle for issuing a power stream intoone end of said chamber, a control nozzle for issuing a control streamin interacting relationship with said power stream for eflectingamplified directional displacement thereof, plural passages locateddownstream of said interaction chamber for receiving fluid flowtherefrom, a substantially wedge shaped flow splitter located betweensaid passages for splitting flow into said passages, a concave tipformed at the converging end of said flow splitter for receiving fluidfrom said power nozzle and a duct extending laterally from at least oneof said passages downstream of the apex of said flow splitter andcommunicating with a pre determined fluid environment, the walls formingsaid duct being substantially parallel.

2. A pure fluid system comprising an interaction chamber for receivingand confining fluid flow, a power nozzle for issuing a power stream intoone end of said chamber, a control nozzle for issuing a control streamin interacting relationship with said power stream for effectingamplified directional displacement thereof, plural passages locateddownstream of said interaction chamber for receiving fluid flowtherefrom, a substantially wedge shaped flow splitter located betweensaid passages for splitting flow into said passages, a concave tipformed at the converging end of said flow splitter for receiving fluidfrom said power nozzle, a duct extending laterally from at least one ofsaid passages downstream of the apex of said flow splitter, the entranceof said duct communicating with said one of said passages and the exitof said duct communicating with a predetermined fluid environment, acusp formed adjacent said entrance of said duct, so that fluid flowingupstream in said one of said passages across said entrance generates avortex in said duct.

3. A pure fluid system comprising an interaction chamber for receivingand confining fluid flow therein formed by a pair of diverging sidewallsand an end wall, a power nozzle communicating with said end wall forissuing a power stream therefrom, at least one control nozzlecommunicating with one of said sidewalls for issuing a control stream ininteracting relationship to said power stream so as to effectdisplacement thereof in said interaction chamber, a substantiallyV-shaped divider located downstream of said power nozzle and havingdiverging edges positioned intermediate said sidewalls so as to formoutput passages, each sidewall extending from said chamber comprising atleast two sections forming a duct thereoetween, the lateral distancebetween the edge of said divider and a downstream section of eachsidewall being greater than the lateral difference between the edge ofsaid divider and an upstream section of a sidewall, a cusp formed by theupstream section of a sidewall and positioned adjacent the entrance tosaid duct so that fluid flowing upstream between said sections creates avortex adjacent the entrance to said duct.

4. The pure fluid system as claimed in claim 3 wherein the convergingend of said V-shaped divider is substantially concave.

5. The pure fluid system as claimed in claim 3 wherein each of saidoutput passages is provided with a duct having a cusp formed adjacentthe entrance thereof so that fluid flowing upstream of said outputpassages generates a fluid vortex in the cusp.

6. The pure fluid system as claimed in claim 5 wherein each duct isformed by a pair of opposed and substantially parallel sidewalls.

7. The pure fluid system as claimed in claim 2, wherein References Citedby the Examiner UNITED STATES PATENTS 2/ 1928 Charette et a1.

1 Sowers.

Woodward.

Adams et a1. 137-815 Boothe 137-815 FOREIGN PATENTS France.

M. CARY NELSON, Primary Examiner.

10 LAVERNE D. GEIGER, Examiner.

S. SCOTT, Assistant Examiner.

1. A PURE FLUID SYSTEM COMPRISING AN INTERACTION CHAMBER FOR RECEIVINGAND CONFINING FLUID FLOW, A POWER NOZZLE FOR ISSUING A POWER STREAM INTOONE END OF SAID CHAMBER, A CONTROL NOZZLE FOR ISSUING A CONTROL STREAMIN INTERACTING RELATIONSHIP WITH SAID POWER STREAM FOR EFFECTINGAMPLIFIED DIRECTIONAL DISPLACEMENT THEREOF, PLURAL PASSAGES LOCATEDDOWNSTREAM OF SAID INTERACTION CHAMBER FOR RECEIVING FLUID FLOWTHEREFROM, A SUBSTANTIALLY WEDGE SHAPED FLOW SPLITTER LOCATED BETWEENSAID PASSAGES FOR SPLITTING FLOW INTO SAID PASAGES, A CONCAVE TIP FORMEDAT THE COVERGING END OF SAID FLOW SPLITTER FOR RECEIVING FLUID FROM SAIDPOWER NOZZLE AND A DUCT EXTENDING LATERALLY FROM AT LEAST ONE OF SAIDPASSAGES DOWNSTREAM OF THE APEX OF SAID FLOW SPLITTER AND COMMUNICATINGWITH A PREDETERMINED FLUID ENVIRONMENT, THE WALLS FORMING SAID DUCTBEING SUBSTANTIALLY PARALLEL.